Electric circuit breaker



y 1942- P. BARTLETT 2,283,717

ELECTRIC CIRCUIT BREAKER Filed Nov. 22, 1940 Fig. I.

I I I6 C h 25 H 25- l9 2 l'v 27 2 m E I Ii/l5 Percy Bartlett,

// 7/ b 1/0 1476. AZMIAH His Attorney.

Patented May 19, 1942 ELECTRIC cmoorr BREAKER Percy Bartlett, Springfield, Pa... assignor to General Electric Company, a corporation of New York Application November 22, 1940, Serial No. 366,656

3 Claims.

My invention relates to electric circuit breakers and more particularly to the contact structure of electric circuit breakers.

Circuit breakers employing reciprocating conducting members have been usedheretofore. In order to make electrical connection with the reciprocating conducting member, sliding contactshave been provided which have assumed various forms. However, difilculties have been encountered when using the sliding contacts of the prior art in conjunction with high-speed circuit breakem for interrupting circuits carrying large amounts of power, for example, such as the circuit breaker disclosed and claimed in the Prince et al. cop'ending applicationySerial No. 303,126, filed November 6, 1939, and. assigned to the assignee of the present application.

In such circuit breakers, it is essential that the sliding contact takes up a minimum space in the direction of reciprocal movement. Furthermore, such sliding contacts should be able to carry large amounts of current without arcing and consequent scorin of the reciprocating conducting member.

It is an object of my invention, therefore, to' provide a new and improved contact structure which will eliminate the dimculties encountered with arrangements used heretofore.

It is another object of my invention toprovide a sliding contact structure for usewith a reciprocating conducting member which requires a minimum amount of space in the direction of such reciprocal movement.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a" better understanding of my invention, reference may be had to the accompanying drawing in which Fig. 1 is a schematic diagram partly in section of a circuit breaker employing the sliding contact structure of my invention, Fig. 2 is an enlarged end view partly in section of the sliding in the above-mentioned Prince et al. application. Circuit breaker l 0 comprises a stationary contact H and a movable contact l2 arranged to be operated so as to draw an arc in an arc chute lit. The stationary or fixed contact I I is connected to a bushing stud H, which, in turn. is associated with a line terminal, not shown. Movable contact or conducting member I2 is arranged to reciprocate for opening or closing the circuit associated with circuit breaker Ill so as to make sliding contact with the contact structure embodying my invention and generally indicated at l5. Contact structure I5 is arranged to be connected through a bushing stud Hi to a line terminal, not shown. Immediately after the separation o1 contacts II and I2, the are drawn therebetween is driven by an air or gas blast from conduit I1 into arc chute l3 against the plurality of partitions l8, which partitions are transverse to the arc gap and the ends of which extend close to the path of movement of the reciprocating or reversible blade l2.

Referring now to Figs. 2 and 3 wherein the sliding contact structure of my invention is 11- lustrated in detail, I have shown the lower end of bushing stud [6 as terminating in a. fork-- tion upon bolt 22, which is inserted in coopercontact structure shown in Fig; 1, Fig. 3 is a v atlng openings provided in sliding contact housing I 9. It will be observed that one surface of reciprocating conducting member l2 and one surface of sliding contact housing l9 are disposed at a ninety degree angle with respect to one another or, in other words, they are perpendicularly arranged.

In order to insure good electrical connection between the sliding contact housing l9 fashioned from the end of bushing stud l6 and reciprocating conducting member I2, I provide a plurality of cylindrical conducting members 23 which are positioned in the right angle formed between sliding contact housing I9 and the two sides of the reciprocating conducting blade I 2. Each of the cylindrical members is provided with an opening 24 therein through which a loosely fitting retaining pin 25 is inserted to keep the rollers in position before the insertion of the reciprocating conducting member l2. The pins 25, which are supported by the sliding contact housing l9, are arranged to fit loosely in the openings 24 of roll-.

era 23 so as to permit free self-alignment of the rollers.

In order to hold the cylindrical members 23 in conducting engagement with both the sliding contact housing I 9 and the reciprocating conducting member I2, I provide spring means 2', one for each cylindrical member 23, which comprise. as illustrated in the drawing, fiat spring members suitably fastened to the sliding contact housing II by means of plates 21 which are bolted to the contact housing. By this arrangement, the spring force supplied to cylindrical conducting members 2! causes these members to engage firmly with both the sliding contact housing I! and the reciprocating conducting member l2, thereby providing good electrical contact therebetween.

. The spring means 28 provides a sort of wedging force for wedging the cylindrical conducting members 2! into the angle formed tween the respective surfaces of sliding contact housing it and the reciprocating blade II, which, in the particular arrangement shown in Figs. 2 and 3 is a right angle. In order to lubricate the sliding contact I! to prevent extraneous dirt from entering the contact housing It, I provide wipers 28 supported by contact housing ll adjacent the edges of the opening 20 through which reciprocating blade l2 moves. These wipers 2| may comprise pieces of felt saturated with lubricating oil.

Although I have illustrated conducting member l2 as of the same cross section throughout its length, it might be desirable in some cases to provide an undercut portion so that the cylindrical members 23 do not frictionally engage with conducting member l2 until shortly before the latter engages with contact II. In such a case, the cylindrical conducting members 23 would assume the dotted positions shown in Fig. 3 and free rotation of the cylindrical members could take place until the portion of conducting member l2 which was not undercut forced them to assume the solid positions shown in Fig. 3, after which they would no longer rotate. By this arrangement, a wiping action would be provided and, furthermore, the rolling action of the cylindrical conducting members 23 would provide for wear to take place all around the periphery thereof rather than at one point.

An increased wedging action of the conductin cylindrical members 23 might be obtained if the angle betweenone of the surfaces of sliding contact housing I! and the surfaces of reciprocating member I 2 were less than ninety degrees, i. e., an acute angle. Accordingly, in Fig. 4, wherein the corresponding parts are designated by the same reference numerals as in Figs. 1 to 3, I have illustrated a modification of my invention in which the angle between the respective surfaces of conducting member l2 and the cooperating portion of sliding contact housing I! is no longer perpendicular by undercutting the surface of the contact housing I9 at 29 so that an acute angle is formed between these respective surfaces. By this arrangement, cylindrical conducting members 23 mounted in this angular space are forced by spring means 26' so as to be wedged between these surfaces disposed at an acute angle with one another so as to provide good electrical contact.

From the above discussion, it will be observed that I have provided a sliding contact I! for an electric circuit breaker employing a reciprocating blade which requires a minimum amount of space in the direction of movement of said reciprocating blade and which will carry large amounts of current in a satisfactory manner, thus eliminating the difficulties encountered in connection with the sliding contacts of the prior art.

While I have shown and described a particular embodiment of my invention as appllied to a sliding contact for electric circuit breakers, I do not desire my invention to be limited to the construction shown and described for it will, of course, be obvious to those skilled in the art that changes and modifications may be made without departing from my invention and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A sliding contact for an electric circuit breaker having a reciprocating conducting mem bet and a stationary support associated therewith comprising means interposed between said support and said conducting member for insuring continuous electrical current conduction therebetween including a plurality of currentconducting members each provided with a curvilinear surface and all loosely mounted on a common shaft, and resilient means for biasing said contacts into engagement with both said support and said conducting member.

2. In an electric circuit breaker, two fixed conducting members, a reciprocating movable contact member carried by one of said fixed conduct ing members and adapted to be moved into contact with the other of said fixed conducting members to close said circuit and out of contact with said other of said fixed conducting members to open said circuit, means carried by said one of said fixed conducting members for guiding and supporting said movable contact member in its reciprocating movement comprising, a plurality of current conducting members each provided with a curvilinear surface and all loouiy mounted on a common shaft and resilient means for biasing said current conducting members into engagement with both said one of said fixed conducting members and said movable contact member to insure continuous electrical current conduction therebetween.

3. In an electric circuit breaker having a fixed contact and a movable contact between which an arc is broken, a stationary conducting support for said movable contact, said support including a sliding contact housing and rolling means positioned below said movable contact, means for imparting reciprocating movement to said movable contact, means interposed between said support and said movable contact for insuring continuous electrical current conduction therebetween, said means including a plurality of current-conducting members each provided with a curvilinear surface and all loosely mounted on a common shaft, and resilient means for biasing said current conducting members into engagement with both said support and said movable contact.

PERCY BARTLETT. 

